Safflower, Carthamus tinctorius L. - Bioversity International

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18 Safflower. Carthamus tinctorius L. A mature achene of common varieties is made up of 33-60% hull and 40-67% kernel. Oil content ranges from 20 to 45% or more of the whole seed. Selection for high oil content in modern cultivars has reduced the pericarp thickness. Seed mass increases rapidly during the first 15 days after flowering. In California, oil content increased 5- to 10-fold during the 10-15 days after flowering (Hill and Knowles 1968). Leininger and Urie (1964) determined that, for their varieties in their growth environment, maximum dry matter accumulation, maximum oil content, maximum germination and minimum hull percentage occurred 28 days after fertilization of a floret, when the seed moisture content was 22-25%. Leaf size varies greatly among varieties and on an individual plant, and ranges typically from 2.5 to 5 cm wide and 10 to 15 cm long. Leaves are usually deeply serrated on the lower stem, but short and stiff, ovate to obovate around the inflorescence, where they form the involucral bracts. Lower leaves are generally spineless, but further up the stem spines develop in the bud stage and become strong, hard spines by full flowering. Varieties that are almost completely free of spines have been developed for hand harvest of floral parts and of seeds in certain geographic regions (e.g. China, nontraditional areas of India). 2.2 Production issues Over the past few decades, fact sheets and production guides have been provided for safflower growers in different countries. A sampling of those published in the past 5 years in North America is given in the literature section. Safflower is generally considered a daylength-neutral, long-day plant. However, the origin of varieties is very important in this connection: summer crop varieties from temperate regions, sown during shortening days as a winter crop in subtropical or tropical regions, have a very long rosette phase (several months), with greatly delayed maturity. Seeding rates vary greatly around the globe, in part related to variety growth habits, growth environments and cultural methods, particularly row spacing. As long as soil moisture reserves are present, safflower compensates for low plant populations by increased branching and other yield component adjustments (Mündel 1969). Seeding rates for optimum production vary from around 10-15 kg/ha in very droughtprone regions, or those where branching is to be encouraged, up to 40-45 kg/ha or even more for irrigated environments, in regions and with varieties showing minimal branching. Germination of safflower seed occurs at temperatures as low as 2-5º C. During the rosette stage, the growing point of the young safflower plant is protected from cold by multiple layers of young leaves and leaf primordia, and temperatures as low as –7ºC do not kill the plant (Mündel et al. 1992). The first few leaves emerging after a frost may show some injury, but the plant recovers and continues to grow quite normally. However, during the elongation phase, even a light frost can cause substantial damage. At the other end of the plant’s development, frost just after flowering (during kernel filling) can dramatically lower yields and oil levels, or kill the seed completely.
Promoting the conservation and use of underutilized and neglected crops. 7. During the early stages of growth, especially during the rosette stage, safflower is a poor competitor with weeds. Numerous weed species, left unchecked, can become taller than safflower and effectively shade the crop, competing for sunlight, nutrients and soil moisture. Weeds can cut safflower yields greatly and can cause complete crop losses. Only a limited number of chemical herbicides are registered for use on safflower, mainly because of the high cost of testing required in a number of countries for this minor crop. In Canada the trifluralins and ethalfluralins are registered for pre-plant incorporation to control a variety of grass and broadleaf weeds; a sethoxydim has been registered for post-emergent control of grassy weeds and volunteer cereals (Blackshaw et al. 1990). Seeding safflower into a firm moist seedbed not only enhances its emergence and stand, but also improves vigour and allows the crop to compete more effectively with weeds. Mechanical or manual control of weeds emerging prior to safflower emergence is advised. Safflower, with its deep taproot and xerophytic attribute of spines, has good drought and heat tolerance. The crop may use considerable amounts of soil moisture, but it does not survive standing water for even a few hours in warm weather (air temperatures above 20ºC), partly owing to the rapid spread of soilborne pathogens such as Phytophthora (Rubis 1981) and Pythium, but also because anaerobic conditions cause plant death very quickly (Mündel et al. 1995). Well-drained, deep, fertile, sandy loam soils support maximum safflower yields. In heavy clay soils, crusting may reduce emergence of seedlings and seeding rates that are higher than normal are needed. In general, if moisture has been limiting, one good irrigation just prior to bloom increases yield significantly. Such a system of ‘protective irrigation’ is used widely in India (A.K. Deshmuk, pers. comm., 1986). Excess rainfall, especially after flowering begins, contributes to a vast array of leaf and head diseases, which reduce yields and even cause crop loss. Kolte (1985) provides a detailed discussion of safflower diseases. Prolonged rainfall during flowering interferes with pollination and seedset, as do high temperatures (i.e. >32ºC) during pollen shedding in the mornings (Mündel et al. 1992). Highest yields, with very low disease infection have been achieved with subirrigation, as practised in the Sacramento Valley of California, USA (A.B. Hill, pers. comm., 1968). Safflower is a long-season crop with a deep taproot that can draw moisture from deep in the subsoil. Thus, it can access and utilize nutrients from below the root zone of cereal crops. Nevertheless, fertilizers tend to increase yields and oil levels, especially in irrigated or higher rainfall areas. Furthermore, in areas afflicted with dryland salinity, safflower uses surplus water from recharge areas, drawing down the moisture with the salts dissolved in it, preventing expansion of saline seeps (Mündel et al. 1992). 2.3 Genetics The outcome of the studies of inheritance of safflower characters is greatly influenced by the selection of parental lines and many sets of parent lines have been used in crosses, especially in diallel crosses. Valid determinations of the heritability, 19
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Safflower, Carthamus tinctorius L. - Bioversity International

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